Start using Pyflakes and Hacking

Instead of globally ignoring pyflakes and
hacking warnings, only blacklist those that trigger
very frequently so far, in order to clean them
up in followup commits. Fix and start gating
on the rest already.

Change-Id: Ied7c7250061e3bf379e8286e8ce3b9e4af817faf

tests/v2/test_members.py

@@ -13,7 +13,6 @@
 #    License for the specific language governing permissions and limitations
 #    under the License.
 
-import errno
 import testtools
 
 import warlock